Emergency SOS Location Notification
If you trigger the emergency SOS but your phone isn’t connected to data or wifi, can your phone still alert the police and your emergency contacts to your location?
Question marked as
No it will not make an emergency SOS call, if you do not have WiFi or Cellular Service On
You can check it yourself by putting in your iPhone in Airplane Mode and Switching your WiFi off.
Use Emergency SOS on your iPhone - Apple Support
https://support.apple.com/en-us/HT208076